Biochemical and Bacteriological Quality of Rohu (Labeo rohita) Head Sauce Produced by Enzymatic and Fermentation Method

Abstract

A sauce was produced by enzymatic and fermentative methods using the heads of freshwater fish rohu (Labeo rohita) with solar salt concentration of 25% (w/ w). Commercial papain (3%, w/w) was used for enzymatic hydrolysis and stored at room temperature for 120 d. Pediococcus pentosaceus FSBP 4-40 (10%, v/w) with the cell concentration of aproximately 8 log cfu ml-1 and dextrose (7.5%, w/w) was used for fermentative production at 37°C for 120 d. Changes in yield, water activity (aw), total valatile base nitrogen (TVB-N), total soluble nitrogen (TSN), non protein nitrogen (NPN), titratable acidity (TA), degree of hydrolysis (DH) and fatty acid composition of both enzymatically and fermentativley produced rohu head sauce was observed. Bacteriological parameters such as total plate count, Escherichia coli, lactic acid bacteria, staphylococci, total halophile count and yeast and mold counts were determined at different time intervels . The result suggested that TSN, NPN, TA and DH significantly increased (p<0.05) in treated samples compared to control. However, aw, pH, moisture, fat, TVB-N, fatty acid concentration and L*, a*, b* values showed changes. The antioxidant properties like total antioxidant activity, 2,2‘-diphenyl-1- picrylhydrazyl (DPPH), super oxide anion scavanging activity and reducing potential of the lyophilized rohu head sauce samples were found to be sigificantly higher (p<0.05) in enzyme/bacteria treated samples than control. Bacterial counts after 120 days were significantly lower (p<0.05) in the fermentatively produced rohu head sauce than enzymatically prepared sauce.